The invention is based on an electrical device for attachment to a holder. A holder, in particular for a monitor in a vehicle, is already known from U.S. Pat. No. 5,288,049. In it, an electrical device in the form of a monitor is slid into a clamp mounted to a vehicle roof and after being slid into place, is secured by means of a lock. When the monitor is being mounted, it must be moved along the clamp along the entire sliding path, i.e. in accordance with its length. In addition, when the monitor is being mounted, the monitor, which is above the head of the installer, must be inserted into the clamp provided for the holder in a precisely fitting manner.